The subject matter disclosed herein relates to an automated brazing system and, more particularly, to an automated brazing system with improved performance and reduced defect rate.
Round tube and plate fin heat exchangers (RTPF) used in air conditioners, heat pumps and refrigeration units generally include a series of long “U”-shaped tubes inserted into a densely arranged pack of fins. The formed tubes, called hairpins, are then circuited (joined) to each other at the opposite end by brazed-in-place return bends. In some cases, straight tubes are used instead, while return bends are brazed at both ends of the tubes. At low production volumes, the tubes are brazed manually. However, such manual brazing process is operator dependant, susceptible to a higher defect rate and unacceptable in the high volume production environments. Therefore, there is cost justification to automate the brazing process when the production rates become sufficiently high.
Since conventional RTPF heat exchangers typically have copper tubes and aluminum fins, the associated brazing process is forgiving due to a wide temperature window between melting points of brazing material and base material of the copper tubes. Brazing automation for aluminum tubes in aluminum tube and aluminum fin RTPF heat exchangers, on the other hand, is new and requires relatively high quality and high precision brazing to assure a leak/defect rate that is comparable to copper/aluminum RTPFs.